we have lot of info on trying to increase the output of the alternatorbut there are better rectifiers regulators out there ( 12 volt items )ever since about 2007 some bikes came with mosfet regulators instead of the shunt type regulators that uses SCRsthe shunt type that uses SCRs have a bad habit of frying itself . shindengen makes the mosfet regulators . the shunt type reg. have a part number that starts with SH the Mosfet types part number starts with FH the smallest mosfet regulator i found is the FH 008EE . it is rated 35 amp they are fitted to CBR 600RR and CBR 1000RR 2007 and up . all other ones are rated 50 amps

Shunt or series regulators can be composed of many various components. Diodes, Bipolar transistors, SCR’s, resistors, capacitors and inductors. There could be a shunt type and a series type that uses the exact same components arranged in different ways. An SCR in the circuit is not necessarily indicative of a shunt regulator.Shunt regulators were the standard for a very long time because they worked, they were good enough, simpler to build and cheaper I think. In the Regulators that I have seen with SCR and FETs' they are being used as switches. I have not found the schematic of any Shendengen rectifier/regulator designed for a single phase circuit, so can't specifically speak to them.

The Shunt type no matter the components will shunt or pass to ground (through a resistance instead of to the load) any current in excess of that needed by the load. By load I mean motorbike systems that use power-battery, lights, ignition etc. These Shunt regulators get a bad rap because they cause the permanent magnet alternator to produce power continuously and therefore generate more heat in the rectifier/regulator and the alternator itself. If well designed, they can work fine and last a long time.

The series rectifier/ regulators can use different schemes to accomplish the regulation, but most I have seen insert a switching component in place of one of the diodes in each conducting path in the bridge rectifier. In this way, when load demand has been met, the control circuit turns off the bridge and no current flows through the stator or the rectifier. This reduces the average current though all the stator and rectifier components and as such reduces the resultant heat. The smarter control circuits will be able turn on the switching component anywhere from zero to the full potential of the stator output and can limit's rectifier output to just what is needed.

Why a MOSFET over an SCR or Bipolar transistor in a series regulator? Speculating here. MOSFETS are more efficient. I know that they are far superior in high frequency applications. They have very quick switch time. They require less drive current at the gate than a standard transistor or SCR. They are not as affected by thermal runaway as a bipolar transistor or scr would be, so would be less inclined to self destruct as you had mentioned. An SCR can only be switched on and will continue to conduct as long as it is forward biased. So the SCR can’t be as precisely controlled as standard transistor or MOSFET which can be turned off even when forward biased.

In the limited searching I have done, many of the available rectifier/regulators don’t tell you which type they are and when they do they don’t provide you a schematic. Shendengen being the exception, but even they don’t show you the control circuits. I think that it is not so much that the rectifier regulator has MOSFETs in it that make it superior, it is that it is a series regulator. MOSFET’s are probably the best device to use here, but a series regulator with SCR’s or bipolar transistors could work fine if well designed.

I guess now that we've discovered some of the best ways to extract the most wattage from a stator, the next logical progression is to discover a suitable modern regulator. I discovered a series style regulator which uses SCR technology, it specs as a 12 volt, series style, intended to be used with a permanent magnet alternators. Rated for 15 amps, and origionally fitted to Kohler small engines, it has 2 AC in pins and one DC out pin and grounds through the housing. I had the schematic earlier from the manufacturer but I've lost it...I'll try in the next couple of days to get it again. ( http://www.waiglobal.com --type kh4309 in search engine on page) Don't quote me exactly, but I think I spent about $45.00 The size is 1.5 inch wide, 3.25 inch long, .75 inch high.

I'm anxious to get my engine spinning so I can test this reg. with my stator, but so far I can only guess what it's going to do.

Shindengen FH reg/recs's are fast becoming the replacement of choice for many problematic stock applications, if you google it you'll be pointed to numerous articles and discussions on many brand forums like Triumph and Ducati as well as a small aftermarket of connector/adapter kits for various bikes. I'd have to assume they'd be quite bulletproof on Ducati singles as it would be operating at only a small percentage of the rated capacity. If you're patient and persistent you can find them on ebay for under $50, I paid $30 for one of mine. They come stock on many different bikes, Eldert mentioned the CBR's and there's also zx10's and zx14's, R1's and FZR's as well as a few big cruisers that are escaping me ATM. Shindengen only has mosfet regulators in 3 phase but they're able to run single phase alts using only two of the three input wires as can be done with many of the three phase scr types. I have an fh008 and an fh010 (from a cbr600 and a zx10), tried one for a short time on the new 'three section series' modded 6 pole alt with combined outputs and it worked fine running a 55w light and an undercharged battery, didn't even get warm. Haven't gotten around to any efficiency testing compared to other reg/recs or plain rec's and didn't test one on the stock unaltered alt.

Did you ever test out the kohler type regulator ? Im curious because I have a spare one in my parts stash... I have a scag zero turn mower, with a kohler command 25hp engine on it that uses that type of regulator. The only thing im curious about is this... The heat sink isn't very big on that reg. because its mounted on the blower housing on those engines so it stays nice and cool there... I may just try it on my duke for kicks, but I was wondering if you had already done so...Thanks for any info you have, Joe

Joe,I have not tried my kohler regulator, though I am optomistic about it's usefulness.Just as I was getting started on my alternator project, I discovered a bad crank in my engine, pulled it out, sent it for rebuild. As soon as crank is back in' I'm quite close to a running engine, and testing that kohler reg.Meanwhile if you try it, let me know your results.I'd also be interested in your alternator configuration?

Bruce, I did try the aforementioned kohler regulator... and it did seem to work, but did get incredibly hot, enough so that I don't think it would live a long life in this application... I don't have any pics, but on my Scag (kohler command ch25 engine) it is mounted right on the blower box, and gets a powerful stream of air blown directly on it, which is probably why the heat sink area is small...

Here is a pic of what i'm running, I bought this from j&n electric, I get the best deal there, but you should be able to make out the kohler/john deere/kubota part #'s and check other places... Also for $4 more I got the pigtail harness, and 3 more locking female spade connectors, so I can use the correct color wires (yellow/yellow/red) and so there will be no splices, it does ground through the case, but I will also have a dedicated ground run to the battery for good measure, mostly because I havent decided what I will mount it to yet, but it may get mounted to fiberglass, hence why I need a ground... This unit is a 15amp reg/rec. and has a much larger alum. case/heat sink... I think 15 is already overkill for this app. but they also have 20, and 25 amp single phase units, that look similar (but cost more) I don't know if j&n sells to the public or not, we are a dealer for there products at work, so I have a login for there site, im not sure if an account is required or not... Only other info is I am running this on 2 dukes one, a 450 Scr, and one "bitsa" if you will, cafe project. On this one im running the 60w mach 1 alt. with combined/isolated grounds..a 7" Lucas headlight bucket from a norton ? or other british bike, cant recall...with a 35/65 watt H6024 Halogen sealed beam in it. Im also running a Dynatek Coil, Petronix ignition pickup, (with stock A.A.U. in place) Led tailight, Led indicator lights, a 14 amp hour 12v Sealed A.G.M. battery (intended for backup lighting/electric fences/etc)

One last thing I have wired up...This was purely overkill/curiosity/planning for the future in case I wanted to ride around all night with the brights on

I have a 25amp/200v PIV Rectifier (Newark Electronics SKU#06m7446, Mfr. #NTE5322) Wired in also, and run through a toggle switch, this is similar to the scheme bob has depicted in an earlier post about getting more output from the w/c alternator. When I flip the switch, the reg./rec. is removed from the circut, and the alt. current is fed directly through this rectifier, then to the battery. I really doubt anyone else will want to do this...but the reg/rec, the pigtail, the switch, the wiring, The sealed beam, the led tail light all cost under $90 which is like FREE compared to the insane prices i've paid for other DUKE parts...

" I have a 25amp/200v PIV Rectifier Wired in also, and run through a toggle switch, this is similar to the scheme bob has depicted in an earlier post about getting more output from the w/c alternator. When I flip the switch, the reg./rec. is removed from the circut, and the alt. current is fed directly through this rectifier, then to the battery. I really doubt anyone else will want to do this... "

____ Actually such switch-bypassing of a regulator and running straight-rectification like that is okay (and possibly more efficient) for when running lights-on at lower RPMs, (so long as a battery is left connected, to help maintain the system's voltage-level). To get an idea of how high you can rev the engine up-to without need of any system v.level-assistance from a regulator-unit, try connecting a DC-voltmeter to your (fairly charged) battery and continually raise engine-RPMs until your meter reads upwards of 13.8-volts, at which point you may then assume that you're making life tough on the battery and could then-thus use a regulator IF such higher voltages are likely to be maintained for much longer than an hour (at-a-time, without at-least an hour's rest between such extended high-charging periods). A 12v.battery, (if not too small), can of-course handle higher voltages than 13.8v for brief-times (such as when speed-shifting), but then (at voltages over 14v) your lighting-lamps' life-expectancy becomes at risk. __ Also, there's really no (required)- reason to need to have to choose between running with EITHER your rect.regulator-unit OR your rect.block, as they could easily be wired-up to run concurrently together, if so desired. ____ If, (on a strong charging-system), it's found that a (somewhat overwhelmed) regulator-unit allows voltages over 13.8v during MOST normal riding RPMs, then it seems that a means for cutting-down available power, is in order. And that could be done with a toggle-switch, so as to be able to choose between either full-wave or half-wave rectification, or, connect/disconnect an (extra) alternator wire-lead to/from the rectifier (as Jap.bikes do). Cuz cutting-down any excess available power-output, may then allow many regulator-types to better cope with their job of keeping the voltage-level down to a more normal working-level (like 13.2-volts).

Sufficient-Cheers,-Bob

PLEASE NOTE...If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,,and if not also included with 'DCT' near bottom as well,then I may edit this post's wording at a later time. - Dct.Bob